One approach towards the treatment of insulin-dependent diabetes is to supplement the patient's defective islets of Langerhans with functionally active islets obtained from histocompatible donors. If this can be done in the clinical setting, we would expect the risk of "diabetic shock" to the patient to be minimized, the lifelong cost of maintenance reduced and the quality of life substantially improved. The success of islet transplantation is dependent upon both the isolation of large numbers of functional islets and upon the preservation of the morphological and physiological integrity of these islets. We are developing high yield methods for isolating islets of Langerhans based on the differential sensitivity of islet cells and acinar cells to freezing. We will define the optimal conditions for the cryogenic storage of rat, dog, pig and human islets of Langerhans using continuous and two-step cooling techniques. The physiological integrity of the thawed islets will be evaluated by their ability to secrete insulin, glucagon and somatostatin in vitro. Cryobiological techniques will be devised to maximize the survival of Beta cells while destroying passenger leukocytes. Such treatment should minimize the probability of immunological rejection subsequent to transplantation. We will continue our development of inexpensive nonisotopic methods (ELISA) for quantitatively assaying the levels of these hormones and we will attempt to utilize the differential response of islets and acinar cells from freezing as a method of separating partially purified islets from acinar cells. When long-term storage of isolated human islets becomes feasible, then tissue banks could be established which would allow sufficient time for cross-matching the frozen tissue with histocompatible insulin dependent diabetes, thus increasing the probability of a successful transplant.